The present invention relates to an electronic component functioning with reflected acoustic waves on a substrate, said substrate having a reflector structure having finger weighting associated therewith.
A surface wave filter designed as a dispersive delay line and an improvement relating to such a filter are disclosed in U.S. Ser. Nos. 377,466, now U.S. Pat. No. 4,427,954, and 472,980, now U.S. Pat. No. 4,484,160; and German application No. P 32 09 962.2, the U.S. Ser. No. 472,980 being incorporated herein by reference. Particularly in the case of the above cited second and third applications, an electronic component functioning with acoustic waves is provided whereby the finger weighting employed to achieve a specific, prescribed transfer function is achieved such that a spacing of finger groups from one another and of individual strip-like fingers from one another is varied relative to a position of the fingers which would correspond to such a component without finger weighting. In the first cited patent application this finger weighting is realized by means of finger length weighting fundamentally known per se. The non-equidistant spacings of fingers or finger groups from one another in this component serve to achieve a prescribed dispersion of said component.
The invention of the German application No. P 32 09 962.2 offers the advantage (apart from a dispersion realized in this component) of providing the finger weighting necessary for the prescribed amplitude function of the transfer characteristic such that the active portions of the individual fingers of the respectively employed digital structure (structures) extends over the entire width of the working area of the electronic component, i.e. over the entire width of the structure (structures) at right angles relative to the primary propagation direction of the acoustic wave. Despite the presence of a finger weighting, disruptive side effects which are connected with finger length weighted structures or with finger dot weighted structures should be avoided.
In the extreme case, given an electronic component according to German application No. P 32 09 962.2, a shift of respectively adjacent fingers relative to one another can be provided in order to realize the necessary finger weighting (related to a non-weighted structure), i.e. a respective finger group to be subjected to finger weighting consists of only two fingers. Thus, maximum band width is achieved for a structure or for a component according to this earlier invention.